LibKet: LibKet - The Quantum Expression Template Library

LibKet (pronounced lib-ket) is a lightweight expression template library that allows you to develop quantum algorithms as backend-agnostic generic expressions and execute them on different quantum simulator and hardware backends without changing your code.

LibKet is designed as header-only C++ library with minimal external dependencies. All you need to get started is a C++14 compiler and, optionally, Python 3.x to execute quantum algorithms directly from within LibKet.

Have a look at the following code snipped to see how easy it is to generate the quantum algorithm for an n-qubit Quantum Fourier Transform (QFT) circuit and execute it on the Quantum Inspire simulator platform using 6-qubits:

// Include main header file
#include <LibKet.hpp>
// Import namespaces
using namespace LibKet;
using namespace LibKet::circuits;
using namespace LibKet::filters;
using namespace LibKet::gates;
// Create generic quantum expression
auto expr = qft(init());
// Execute QFT<6> on the Quantum-Inspire simulator platform
try {
  QDevice<QDeviceType::qi_26_simulator, 6> qi; qi(expr);
  utils::json result = qi.eval();
  QInfo << result << std::endl;
  QInfo << "job ID     : " << qi.get<QResultType::id>(result)               << std::endl;
  QInfo << "time stamp : " << qi.get<QResultType::timestamp>(result)        << std::endl;
  QInfo << "duration   : " << qi.get<QResultType::duration>(result).count() << std::endl;
  QInfo << "best       : " << qi.get<QResultType::best>(result)             << std::endl;
  QInfo << "histogram  : " << qi.get<QResultType::histogram>(result)        << std::endl;
} catch(const std::exception &e) {
  QWarn << e.what() << std::endl;
}

In Dutch, 'Quantum' is spelled 'Kwantum', which explains the spelling LibKet. The name is an allusion to the famous bra-ket notation that is widely used for expressing quantum algorithms.